The goal of the proposed research is to investigate the link between language learning, on the one hand, and the ability to categorize and individuate objects on the other. For adults, conceptual representations of object kinds are lexicalized as count nouns. These representations provide criteria for categorization and individuation. Some have proposed that children are aided in the process of lexical acquisition by linguistic constraints that limit the possible meanings they consider when they hear a novel label. In particular, it has been suggested that when children hear a label applied to an object, they assume it refers to that object and others of the same kind (e.g., Markman, 1989; Waxman, 1994). Alternatively, labels may facilitate categorization and individuation by simply increasing infants attention to all perceptual object features, with specific relations between count nouns and object kinds being learned through experience with language. The proposed experiments examine whether labeling facilitates infant's ability to categorize and individuate objects. Further, they address the issue of whether labeling is specifically linked to object kind concepts early in lexical acquisition or whether it mediates attention to a range of perceptual properties. These experiments will shed light on the early development of the processes that underlie the acquisition both of language and conceptual knowledge.